Field of the Invention
The present invention relates to a new antimalignant agent. More particularly, the present invention relates to a process for preparing a new active substance obtained by cultivating Staphylococcus epidermidis STF (Bikoken Deposit No. 3706; ATCC 31310) in a liquid medium.
The above substance exhibits an effect of inhibiting leukemia and malignant tumor.
The present invention is based on a finding that in a leukemia patient, leukemia cells were reduced in number remarkably unexpected when the patient developed a boil, and finally, the leucocyte number of the patient became normal.
The inventors separated a strain of microorganism from the boil of this patient, cultivated the same, administered a filtrate of the culture solution to animals affected by induced leukemia and confirmed that the administration of the filtrate gave rise to such effects on the affected animals such as reduction in amount of leukemia virus, reduction in number of leukemia cells, recovery of leukemia affected organs, prolongation of life and increase in number of surviving animals. On continuation of the investigations, the inventors have further found that said filtrate is effective not only for leukemia but also generally for other malignant tumors.
The inventors concentrated the filtrate of the culture solution, fractionated water-soluble substances considered to be active ingredients into a number of fractions and isolated and purified the substances to prove that the substances have the above described antimalignant activity.